44 ANALYSIS AND ADULTERATIONS OF BUTTER. 



Dilute sulphuric acid was added, and the strongly acid 

 liquid was then subjected to distillation. Here again the 

 bumping of the boiling liquid endangered the success of 

 the experiment. The acidity of the distillate was deter- 

 mined by means of standard soda solution, and calculated as 

 butyric acid. Obtained 6 '52 per cent, of butyric acid. 



This figure cannot be considered as accurate, since the 

 violence of the ebullition rendered it impossible to carry the 

 distillation to the end, the distillate being still acid when the 

 experiment was stopped. Although incomplete, this first 

 determination proved beyond doubt that the quantity of 

 volatile acids contained in butter-fat was much more con- 

 siderable than was supposed. 



Experiment 2. 9*680 grammes of butter-fat were saponified 

 in a flask as before. The soap was decomposed, the liquid 

 heated until the fatty acids floating on the surface were just 

 fused to a clear oil, which then was allowed to cool and 

 solidify. The fatty acids were then removed and washed by 

 means of boiling water. The filtrate and washings were 

 subjected to distillation, and the acidity of the distillate 

 determined as described. The acidity of the distillate, 

 however, never quite disappears, and when so great a concen- 

 tration has been reached, that the glycerin in the liquid begins 

 to decompose, the acidity becomes again very considerable, 

 doubtless from the production of acrylic acid. 6 '7 6 c.c. of 

 standard soda solution were neutralised by the distillate. 

 1000 c.c. of this standard solution are equivalent to 88 

 grammes of butyric acid; 6 '76 c.c. therefore = 0*59488 

 gramme, or 6*146 per cent. 



Experiment 3. 7*494 grammes of the same butter-fat 

 yielded 7*480 per cent, of volatile acids. 



Experiment 4. 10 grammes of another butter-fat gave a 

 quantity of volatile acids neutralising 5*79 c.c. of standard 

 soda solution equal to 5*09 per cent, of butyric acid. 



